Examples of pertinent patents which were considered before filing this application are:
Humbert U.S. Pat. No. 3,456,800 describes a two-way valve within the central cylindrical screen of an oil filter. Oil flows longitudinally within the cartridge between the perforated outer shell and the solid outer shell.
Pall U.S. Pat. No. 3,262,567 describes a two-way valve within the central screen cylinder of a filter cartridge, which uses a substantially non-distensible annular frustoconical spring disc as the relief valve.
Pall U.S. Pat. No. 3,262,564 describes a particular bypass arrangement near a filter mount.
Baldwin U.S. Pat. No. 3,557,957 shows a specific two-way valve design.
Baldwin U.S. Pat. Nos. 3,557,958 and 3,608,724 describe and claim relief valves mounted at the head end of the filter to communicate the passageways upon excess pressure.
U.S. Pat. Nos. 3,262,563, 3,272,336, 3,370,708 and 3,146,194 were selected for their general showings of interest.
The remaining patents were selected to show two-way valves to be generally well known in the automotive art. Most of these valves are applicable to radiator cap type devices.